Arsenal's new signing Mikel Merino is set to be out for several weeks after suffering a fractured shoulder in his first training session. (More Football News)
The midfielder, who joined from Real Sociedad in a £31.6million deal earlier this week, sustained the injury in a clash with Gabriel Magalhaes.
Merino had been expected to make his debut for the Gunners against Brighton on Saturday, but Mikel Arteta confirmed that would not be possible.
"Very unfortunate," Arteta told a news conference. "On Thursday, he had a collision, and he has a shoulder injury, unfortunately.
"It looks like he's going to be out for a few weeks. First session. He was really excited, and everything was looking really good.
"He landed on the floor and Gabi landed on top of him, and it looks like he has a small fracture, probably.
"We have to see [how long he is out for]. He was in so much pain. We'll have to do some more tests on that and then we'll have more conclusive answers."
Arsenal have also announced the signing of Neto on a season-long loan deal from Bournemouth following Aaron Ramsdale's departure to Southampton.
The goalkeeper started the Cherries' first two Premier League games of the season, making 11 saves and conceding just twice.
In 63 appearances for Bournemouth in all competitions, he kept 13 clean sheets and helped them to a 12th-place finish in the top-flight last season.
